Photographic gelatin-n-vinyllactam silver halide emulsions containing phenolic antifoggants



United States Patent ()7 PHOTOGRAPHIC GELATIN-N-VINYLLACTAM SIL- VER HALIDE EMULSiONS CONTAINING PHE- NOLIC ANTIFOGGANTS Frederick Charles Forsgard, New Brunswick, N.J., assiguor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Aug. 27, 1958, Ser. No. 757,460

4 Claims. (Cl. 96-409) This invention relates to improved gelatin silver halide emulsions containing a poly-N-vinyllactam having 4 or 5 carbon atoms in the heterocyclic ring and fog inhibiting amounts of a monohydric or dihydric phenol anti-fogging agent.

It has been found that when a substantial percentage of the gelatin present in aqueous photographic emulsions 1 is replaced by a poly-N-vinyllactam of the above class the resulting photographic silver halide emulsions have markedly increased covering power. The maximum density, contrast and efiective speed of these poly-N-vinyl-lactam modified gelatin emulsions is also improved. However, applicant has found that such modified gelatin emulsions show a greater tendency to fog under conditions of storage, particularly conditions of high temperature and high relative humidity such as is encountered in storage in the tropical regions of the earth.

An object of this invention is to provide a simple and effective process for reducing the fogging tendencies of gelatino silver halide photographic emulsions containing poly-N-vinyllactams having 4 to 5 carbon atoms in the heterocyclic ring. Another object is to provide such a process which uses available chemical compounds of simple structure. Yet another object is to provide such a process which involves simple mixing procedures. A further object is to provide photographic gelatino silver halide emulsions containing substantial amounts of poly- N-vinyllactams which have enhanced covering power and contrast characteristics and which do not evidence any substantial increase in fog or loss in speed under high temperature or humidity conditions during storage. Still further objects will be apparent from the following description of the invention.

It has now been discovered, in accordance with the present invention, that photographic gelatino silver halide emulsions containing 8 to 50% by weight based on the weight of total solids in the emulsion of a water-soluble N-vinyllactam polymer containing 4 to 5 carbon atoms in the heterocyclic ring having an average molecular weight of at least 20,000 up to 200,000 or more, enhanced covering power and contrast and being stabilized against fog can be made by admixing with the emulsion small amounts from 5 to 50 millimoles per mole of silver halide of a phenol' antifoggantn The mono or dihydric phenol antifogging agents can be added to the aqueous gelatin/poly-N-vinyllactam silver halide emulsion or dispersion at any time but are preferably added to the aqueous molten or liquefied emulsion after it has been brought to its maximum sensitivity and just prior to coating onto a suitable support to form a photographic film, plate or paper. Other emulsion adjuvants e.g., sulfur sensitizers, hardeners and optical sensitizing agents can be added to the emulsions previously, simultaneously or subsequent to the addition of the phenol. S

The phenol antifogging agents can be added from ethanol solution (e.g., 2% by weight) or in some cases can be added to the emulsions described above. A particularly useful class of monohydric phenols wherein the amass)? Patented July 10, 1962 ice hydroxyl group is attached to a benzene nucleus can contain a hydrocarbon substituent in the para-position to the hydroXyl group and have one, two or three of the remaining nuclear hydrogen atoms substituted by hydrocarbon groups. Among the hydrocarbon substituents which may be present in -the para-position and in the other positions of the benzene ring are alkyl radicals of 1 to 18 carbon atoms, e.g., methyl, ethyl, n-propyl, isopropyl, t-butyl, sec-amyl, t-amyl, t-octyl, n-nonyl and n-dodecyl; aryl, e.g., phenyl, naphthyl and biphenyl; aralkyl, e.g., benzyl, u-cumyl and naphthylmethyl, and cycloalkyl, e.g., cyclopentyl and cyclohexyl. Specific compounds of this type are described below and in as-. signees Smith application Serial No. 656,195, filed May 1, 1957, U.S. Patent 2,955,037, Oct. 4, 1960.

Another and related class of phenol antifogging agents which are particularly useful in accordance with the present invention are the hydrocarbon-substituted mono nuclear monohydric phenols of at least 10 carbons wherein the hydrocarbon substituent is in one of the-positions ortho and metato the hydroxyl group and theother positions of the benzene ring are unsubstituted. These phenols have the general formula:

wherein one of the radicals R and R is hydrogen and the other is ahydrocarbon radical of at least 4 carbon atoms. The hydrocarbon radicals may be alkyl, cycloalkyl, aryl and aralkyl. The alkyl radicals may contain 4 to 12 or more carbon atoms and suitable alkyl radicals are t-butyl, sec-amyl, t-amyl and t-octyl, n-nonyl and n-dodecyl; Suitable cycloalkyl radicals are cyclopentyl and cyclohexyl. Useful aryl radicals include phenyl, naphthyl and biphenyl. Suitable aralkyl radicals include benzyl, u-cumyl and naphthylmethyl. Suitable specific compounds of this type are described below and in assignees copendingSmith application Serial No. 656,181, filed May 1, 1957 abandoned but refiled as continuationin-part US. application Ser. No. 859,108, Patent 2,965, 487, Dec. 20, 1960.

Yet another class of suitable phenols having anti-fogging properties are the bisphenols of the general formula Where Q is a direct carbon-to-carbon linkage S-- O-, (---CH,,--) where n is 1 to 10, or

aryl, and the hydroxyl groups preferably are in the oor ,p-position to the radical Q.

In the above formula suitable alkyl radicals include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, n-hexyl, n-octyl and t-octyl. Useful aryl radicals include phenyl and naphthyl, and suitable cycloalkyl radicals are cyclopentyl and cyclohexyl.

Many of the bis-type phenols useful in the invention are commercially available and others can be made in like manner by any of the known prior art procedures including those described in British specification 621,004 and 622,977; U.S. Patent 2,506,486 and those described in I. Am. Chem. Soc. vol. 54, 4325-34 (1932) and vol. 59, 1114 (1937) and Proc. Roy. Soc. vol. 129B, 528- 538 (I940). The use of such bis-type phenols in gelatinosilver halide emulsions is described in Smith U.S. Patent 2,955,038, Oct. 4, 1960.

The invention is not limited to any particular type of light-sensitive silver halide as it is useful with silver chloride, silver bromide, silver iodobromide, silver chlorobromide, silver iodide, etc., emulsions and mixed emulsions of these types. It is particularly efficacious in silver iodobromide emulsions containing about 2 mole percent iodide and the rest bromide. These emulsions may be sensitized by means of chemical sensitizing agents, e.g. noble metal sensitizers, e.g., gold salts, e.g., chlorauric acid and auric trichloride, may bepresent in association with sulfur sensitizers, e.g., sodium sulfite, thiosinarnine, allylthiourea, sodium thiosulfate, allyl thio- 'carbamate, alkali metal thiocyanates and sodium sulfide,

these sensitizers to be used in amounts up to 0.005% based on the weight of the silver halide. Moreover, the silver halide emulsions may contain one or more optical sensitizing agents, e.g., cyanine, carbocyanine, merocyanine, pseudocyanine, cyazine, etc., dyes.

In general, the finished emulsions will contain on a dry basis, by weight, 8 to 50% poly-N-vinyllactam, 30 to 70% silver halide and to 60% gelatin and 5 to 50 millimoles per mole of silver halide of the phenol antifogging agent.

The invention will. now be illustrated in and, by the following examples wherein the parts and percentages stated are by weight unless otherwise indicated. The preparation of the emulsions, coating and storagev of the photographic elements were carried out in the absence of actinic radiations. Also the covering powersshown in the following tables of the examples havebeen determined on the basis of 40 mg. of developed silver per square decimeter.

Example 1 A high speed gelatino-silver iodobromide (about 2 mole percent iodide, 98% bromide) was digested with an organic sulphur sensitizing compound and gold chloride. After digestion the emulsion was divided into three parts. One part was treated with 45.5 grams of poly-N- vinyl-Z-pyrrolidone having an average molecular weight of approximately 45,000 per mole of silver halide. To a second part of emulsion were added 45.5 grams of poly- N-vinyl-2-pyrrolidone and 18 millimoles of resorcinol per mole of silver halide. The third part containing neither of the above additions was used as a control. The emulsions were coated on cellulose acetate film base and were exposedto X-rays in the presence of an intensifying screen at two difierentintensity levels through an aluminum /2 step wedge. The exposure of greater intensity has been designated as No. 2 and that of lower intensity and longer time as No. 1.

The coatings were developed for 5 minutes in a developer of the following composition:

N-methyLp-aminophenol hydrosulfate grams 3 Anhydrous sodium. sulfite do 50 Hydroquinone do 9 Anhydrous potassium carbonate do 50 Potassium bromide do 4.5

Water to make--- ml 1000 The coatings were tested fresh, after one month of room aging, and after one week at F. and 65% relative humidity (R.H.) The aged materials were exposed and developed as above. Results of tests for speed, gamma and fog before and after the storage treatment of each of the samples are given below. Speed is given in terms of a reciprocal of exposure at a density of 0.7.

FRESH RESULTS No. 2 exposure No. 1 exposure Cov- Compound Amount Fog erlng per mole power Speed Gamma Speed Gamma Oontrol None"-.- 830 2. 79 450 2. 31 .05 30. 8 Polyvinyl 45.5 g 800" 4. 64 460 3.77 .07 39. 5

:(lgne I plus 45.5 g. (I), 800 4. 31 460 3. 52 06 39. 0

resorei 18 millinol. moles.

ONE MONTH ROOM AGING No. 2 exposure No. 1 exposure Fog Speed Gamma Speed Gamma Control 830 2. 59 I 460 2.25 .09 I 880 3. 86 510 3. 32 17 I plus resoreinol 840 3. 89 550 3. 21 10 ONE WEEK AT 120 F. AND 65% R.H.

1 Fog Contr .22 T 1. 42 I plus phenolic compound 54 Example 2 FRESH RESULTS No. 2 exposure No. 1 exposure Cov- Oompound Amount Fog ering per mole power Speed Gamma Speed Gamma 0011501-.-- None 780 3.51 360 2. 64 .06 32.5 I 45.5g 830 4.28 410 3.42 .10 40.0 I-l-phenoL- 45.5 g. (I), 830 3. 84 460 3.16 .08 39.5

20 millimoles ONE MONTH ROOM AGING No. 2 exposure No. 1 exposure Fog Speed Gamma Speed Gamma Control 710 3. 35 360 2. 76 05 840 3. 73 500 3.26 19 I+phen01 com- 780 3. 57 470 3. 00 09 pound.

ther of these additions was made to a third part of the emulsion.

Coating, exposure, development and againg were carried out as in Example 1.

ONE WEEK AT 120 F. AND 65% R.H. ONE WEEK AT 120 F. AND 65% 3.11.

Fog Fog Contr 05 5 Contr 22 T .76 r 1.42 I-l-phpn nl 38 I+phenol 1. 04

Example 3 Example 5 1 1 s t g i gg sfi gg 2 3. 2: 5 2 3: 10 A gelatino-silver iodobromide emulsion digested with if. t 11S i at with sulphur and gold sensitizing compounds was divided into Z i z j i g three parts. One part was treated with 45.5 grams of 1 e p f Signer g g 5 a Second the poly-N-vinyl-Z-pyrrolidone described in Example 1 E g: e 5 ms of the 15 per mole of silver halide. To a second part of the emulp 01 g j gfi 1 i i 14m, i L sion there were added 45.5 grams of the polymer and p land 6 9 of t 2 b61101 millimoles of 3,4 dirnethyl phenol per mole of silver P e 0 e n v y y p p halide. Neither of these additions Was-made to a third mole of silver halide. None of these additions was made art f th I to a third part of the emulsion p o e emu 51cm Coating, exposure, development and aging were carried Coatmg, exposure, development and aging were camed 20 out as m Example 1. out as in Example 1.

FRESH RESULTS FRESH RESULTS No. 2 exposure No. 1 exposure Cov- No. 2 expos 1 exposure 9V- Compound Amount Fog ering Compound Amount FOE eflng per mole power P mole power Speed Gamma Speed Gamma Speed Gamma Speed Gamma o n l N n 2,79 450 2,31 ,05 mg Control None 780 3.51 360 2.64 .06 29.0 I 45.5 g 800 4.64 460 3.77 .07 39.5 5.5g 830 4. 20 410 3.42 .10 37.0 I+phen0l 45.5 g. (I), 800 4.16 460 3.26 .06 39.0 30 +P e 0), 88 4.16 460 3.45 .10 36.5

30 mil- 11111- limoles. hmoles ONE MONTH ROOM AGING ONE MONTH ROOM AGING No. 2 exposure No. 1 exposure g 2 exposure No. 1 exposure F Speed Gamma Speed Gamma 7 Speed Gamma Speed Gamma 830 2. 59 830 2. 59 .09 I 880 3.86 880 3.86 .17 g: g: H'phen 26 26 11 I-l-phenol 800 3. 34 500 3. 09 I 0 Example 4 a A gelatino-silver iodobrornide emulsion digested with ONE WEEK AT 1200 AND 65% sulphur and gold sensitizing compounds was divided into three parts. One part was treated with 45.5 grams of the poly-N-vinyl-Z-pyrrolidone described in Example 1 per 0 1 mole of silver halide. To a second part of the emulsion T :92 there were added 45 .5 grams of the polymer and 9 milli- 1+nhemfl .66 moles of p-t-butylphenol per mole of silver halide. Nei- Example 6 FRESH RESULTS No. 2 exposure No. 1 exposure Cov- Oompound Amount Fog eriug per mole power Speed Gamma Speed Gamma Oontro1 None 780 3.51 360 2. 64 .06 29.0 I 45.5 g 830 4. 28 410 3. 42 10 37.0 I+phen01 45.5 g. (I), 820 3. 86 460 3. 28 .08 38.0

limoles.

ther of these additions was made to a third part of the emulsion.

Coating, exposure, development and aging were carried out as in Example 1.

ONE MONTH ROOM AGING FRESH RESULTS No. 2 exposure N0. 1 exposure N o. 2 exposure No. 1 exposure Cov- Fog Compound Amount Fog ering per mole power Speed Gamma Speed Gamma 5 Speed Gamma Speed Gamma 710 3. 35 360 2.70 .05 Control.... None 800 3.11 390 2.49 .06 25.5 840 3.73 500 3. 2e .10 I 45.5 850 4.00 450 3.28 .10 35.4 I-l-phenol 710 3.00 530 3.10 .09 1 plus 45.5 g. (I), 350 3.85 490 3.03 .08 35.1

phenol 2 0 millrmoles ONE WEEK AT 120 F. AND 65% RE.

ONE MONTH ROOM AGING Fog N0. 2 exposure No. 1 exposure Fog Contr .05 T .76 Speed Gamma Speed Gamma I plus phenol.. 38

Control 750 3. 22 390 2. 45 05 800 3. 55 440 2. 03 14 E a l 7 I plus phenol 770 3. 47 440 2. 70 .08 A gelatino-silver iodobromide emulsion digested with sulphur and gold sensitizing compounds was divided into ONE WEEK AT 120 F. AND 55% EH.

three parts. One part was treated with 45.5 grams of the poly-N-vinyl-Z-pyrrolidone described in Example 1 Fog per mole of silver halide. To a second part of the emul- 25 sion were added 45.5 grams of the polymer and 10 milli- Contr .20 moles of 4 4' iso ro lidene-bis henol er mole of silver T 3 a p Py p I plus phenol 62 hahde. Neither of these additions was made to a third part of the emulsion.

Coating, exposure, development and aging were carried ExamP 9 out as m Example A gelatino-silver iodobromide emulsion digested with sulphur and gold sensitizing compounds was divided into FRESH RESULTS three parts. One part was treated with 45.5 grams of the poly-N-vinyl-Z-pyrrolidone described in Example 1 2 exposure exposure E per mole of silver halide. To a second part of the emul- Oompound Amount Fog ermg per mole power S1011 there were added 45.5 grams of the polymer and Speed Gamma Speed Gamma 10 millimoles of m-tabutylphenol per mole of silver 0 N halide. Neither of these additions was made to a third ontrolone 780 3.5 360 2. 64 .06 29.0 I 45.5 830 4. 28 410 3.42 .10 37.0 40 part of emulslon' 1 31 1 15 1 45. in 830 4.01 440 3.09 .08 38.0 Coating, exposure, development and aging were carried p eno m 0165 out as in Example 1.

FRESH RESULTS ONE MONTH ROOM AGING No. 2 exposure No. 1 exposure 00v- Compound Amount Fog ering N9-2eXDvS11re No-lexposure Fog perfnole Speed Gamma Speed Gamma power Speed Gamma Speed Gamma Gontrol None 800 3.11 390 2.49 .00 25.5 5O 45.5 850 4.00 450 3. 2g .10 35.4 gig g2 1 8 1 1 1: 45. r 350 3.91 400 3.11 .09 34.8 780 31 79 530 31 20 I 10 moles 55 ONE MONTH ROOM AGING ONE WEEK AT 120 F. AND 65% RH.

No. 2 exposure N o. 1 exposure Fog Speed Gamma Speed Gamma Control 750 3. 22 300 2. 05 I plus pheml I 800 3. 440 2. 93 14 I plus phenol 830 3. 84 460 2. 85 10 Example 8 A gelatino-silver iodobromide emulsion digested with 5 ONE WEEK AT R AND sulphur and gold sensitizing compounds was divided into three parts. One part was treated with 45 .5 grams of the Fog poly-N-viny-l-Z-pyrrolidone described in Example 1 per mole of silver halide. To a second part of the emulsion there were added 45.5 grams of the polymer and 20 milli- I Plus phenol--- .63 moles of p-benzylphenol per mole of silver halide. Nei- Example 10 A gelatinO-silver iodobromide emulsion digested with sulphur and gold sensitizing compounds was divided into three parts. One part was treated with 45.5 gramsof the poly-N-vinyl-Z-pyrrolidone described in Example 1 per mole of silver halide. To a second part of the emulsion were added 45.5 grams of the polymer and 20 millimoles of 4,4'-n-butylidine-bis (Z-t-butyl-S-methylphenol) per mole of silver halide. Neither of these additions was made to a third part of the emulsion.

Coating, exposure, development and aging were carried out as in Example 1.

A gelatino-silver iodobromide emulsion digested with sulphur and gold sensitizing compounds was divided into three parts. One part was treated with 45.5 grams of the poly-N-vinyl-Z-pyrrolidone described in Example 1 per mole of silver halide. To a second part of the emulsion were added 45.5 grams of the polymer and 20 millimoles of 2,2-methylene-bis '(4-t-butyl-6-methylphenol) per mole of silver halide. Neither of these additions was made to a third part of the emulsion.

Coating, exposure, development and aging were carried out as in Example 1.

' FRESH RESULTS N0. 2 exposure No. 1 exposure Cov- Oompound Amount Fog errng per mole power Speed Gamma Speed Gamma Control. None 800 3. 11 390 2. 49 .06 25. 5 I 45.5 g. 850 4. 450 3. 28 10 35. 4 I plus 45.5 g. (I) 770 4. 30 400 3. 61 08 32. 5

phenol 20 millimoles ONE MONTH ROOM AGING No. 2 exposure No. 1 exposure Fog Speed Gamma Speed Gamma t 01 750 3.22 390 2. 45 .05 33 800 3. 55 440 2. 93 14 I plus phenol 720 3. 96 400 3. 20 08 ONE WEEK AT 120 F. AND 65% RH.

Fog

l 26 9 95 I plus phenol..- 56

As will be apparent from the above description, the invention is not limited to the use of the specific copolymers and homopolymers of the examples as various other such polymers can be used, e.g., poly-N-vinylcaprolac- 10 tam, poly-N-vinylvalerolactam and poly-N-vinyl-S-methyl-Z-pyrrolidone and copolymers of two or more of the corresponding monomers. Also, copolymers of the latter with vinyl salicylate, vinyl acetate, vinyl alcohol, vinyl oxazolidone, methyl acrylate, acrylamide, methacrylamide, acrylonitrile, vinyl chloride, vinylidene chloride, and styrene containing at least by Weight of the poly-N- vinyllactam. The N-vinyl-oxazolidone can be prepared by the method described in J. Org. Chem.'22, 849 (1957).

.An advantage of this invention is that it provides a simple and effective way of improving the stability and aging characteristics of gelatino silver halide photographic emulsions containing substantial amounts of poly- N-vinyllactams. It enables one to obtain the advantages of the covering power of such emulsions and overcomes their tendency to fog during normal or tropical storage conditions. The invention does not require expensive chemicals or involved procedures and can be carried out by the ordinary technician. Still further advantages will be apparent from the above.

What is claimed is:

1. A photographic silver halide emulsion comprising on a dry-weight basis 30% to 70% silver halide, 10% to 60% gelatin, 8% to 50% of an organic Water-soluble addition polymer taken from the group consisting of homopolymers of at least one N-vinyllactam containing 4 to 5 carbon atoms in the heterocyclic ring and copolymers of such an N-vinyllactam with an ethylenically unsaturated compound taken from the group consisting of vinyl salicylate, vinyl acetate, vinyl oxazolidone, methyl acrylate, acrylamide, methacrylarnide, acrylonitrile, vinyl chloride, vinylidene chloride and styrene containing at least 80% by weight of said N-vinyllactam, and 5 to 50 millimoles per mole of silver halide of a phenol antifogging agent taken from the group'consisting of (a) a hydrocarbon-substituted monohydric phenol of at least 10 carbon atoms having a hydrocarbon substituent in the para-position to the hydroxy group and 0 to 4 additional hydrocarbon substituents in the remainder of the benzene ring, said hydrocarbon substituents being the sole substituents in said phenol and being members taken from the group consisting of alkyl, aryl, aralkyl and cycloalkyl substituents, (b) hydrocarbon-substituted mononuclear monohydric phenols of at least 10 carbon atoms wherein the hydrocarbon substituents contains 4 to 12 carbon atoms and is in one of the positions orthoand metato the hydroxyl group and other positions of the benzene ring are unsubstituted, (c) a compound of the general wherein Q is a member taken from the group consisting of a direct carbon-to-carbon linkage, --O, -S-, -(CH where n is 1 to 4 and where each of R and R is alkyl of l to 18 carbon atoms, and R and R" are each a member taken from the class consisting of hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl and aryl, and (d) resorcinol.

2. An emulsion as defined in claim '1 wherein said silver halide is silver iodobromide.

3. An emulsion as defined in claim 1 wherein said polymer is poly-N-vinyl-Z-pyrrolidone.

4. An emulsion as defined in claim 1 wherein said phenol is resorcinol.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Smith Oct. 4, 1960 Smith Oct. 4, 1960 Smith Dec. 20, 1960 FOREIGN PATENTS Great Britain Feb. 18, 1953 OTHER REFERENCES Mees: The Theory of Photographic Process, page 679, The Macmillan Co., 1954. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION COMPRISING ON A DRY-WEIGHT BASIS 30% TO 70% SILVER HALIDE, 10% TO 60% GELATIN, 8% TO 50% OF AN ORGANIC WATER-SOLUBLE ADITION POLYMER TAKEN FROM THE GROUP CONSISTING OF HOMOPOLYMERS OF AT LEAST ONE N-VINYLLACTAM CONTAINING 4 TO 5 CARBON ATOMS IN THE HETEROCYCLIC RING AND COPOLYMERS OF SUCH AN N-VINYLLACTAM WITH AN ETHYLENICALLY UNSATURATED COMPOUND TAKEN FROM THE GROUP CONSISTING OF VINYL SALICYLATE VINYL ACETATE VINYL OXAZOLIDONE METHYL ACRYLATE ACRYLAMIDE METHACRYLAMIDE ACRYLONRITRILE VINYL CHLORIDE VINYLIDENE CHLORIDE AND STYRENE CONTAINING AT LEAST 80% BY WEIGHT OF SAID N-VINYLLACTAM AND 5 TO 50 MILLIMOLES PER MOLE OF SILVER HALIDE OF A PHENOL ANTIFOGGING AGENT TAKEN FROM THE GROUP CONSISTING OF (A) A HYDROCARBON-SUBSTITUTED MONOHYDRIC PHENOL OF AT LEAST 10 CARBON ATOMS HAVING A HYDROCARBON SUBSTITUENT IN THE PARA-POSITION TO THE HYDROXY GROUP AND 0 TO 4 ADDITIONAL HYDROCARBON SUBSTITUENTS IN THE REMAINDER OF THE BENZENE RING, SAID HYDROCARBON SUBSTITUENTS BEING THE SOLE SUBSTITUENTS IN SAID PHENOL AND BEING MEMBERS TAKEN FROM THE GROUP CONSISTING OF ALKYL ARYL, ARAKYL AND CYCLOALKYL SUBSTITUENTS, (B) HYDROCARBON-SUBSTITUTED MONOCULEAR MONOHYDRIC PHENOLS OF AT LEAST 10 CARBON ATOMS WHEREIN THE HYDROCARBON SUBSTITUENTS CONTAINS 4 TO 12 CARBON ATOMS AND IS IN ONE OF THE POSITIONS ORTHO-AND META- TO THE HYDROXYL GROUP AND THE OTHER POSITIONS ORTHO-AND META- TO RING ARE UNSUBSTITUTED, (C) A COMPOUND OF THE GENERAL FORMULA: 